Shock Valving 101 and the 07 Apex RTX vs REV-XP MXZ X

[Ding]

Anybody got any stack suggestions for the 136 Mono RA shock with the big boy spring?

 

[jaydaniels]

Anybody have any reviews on how the 06 RTX rides. I realize it has the Mono rear skid. Anyone have the shockes re-valved on this skid and if so was it a big improvement?

 

[1litre]

Hello Rex,

Thank you for the information on the shock revalving.

My shocks are currently at a performance "Ski-doo" dealer for rebuild/revalve. I ride and weigh the same as you. I am using your second revalve suggestion (saddlebags) for the main shock.

Would you be willing to share your tweaked valving for the center spring shock? Also is it necessary to replace the center shock spring with a higher rated version? As you posted you re-arched your torsion springs, what method was used? Do you simply bend them with a pipe placed over the long leg of the spring?

Also you were going to post pictures of the reinforced front and rear skid arms, do you have any available to post or email me?

Thank you greatly for any assistance. I love the sled except for the ride. I am tired of my ski-doo buddies heckling me.

 

[beerguy]

I also have been suffering through the miserable stock Pro Active CK suspension on my '07 RTX and am very pleased to hear something can be done about it!

I just got off the phone with Mike Carver and he recommends a dual stage set up on both shocks, as opposed to the triple stage ReX detailed for us.

Any comments?

 

[morg]

Hi. Great information Rex.
I have ohlins on my 08 Ltx Gt. My only real beef is the occasional bottoming out. I'm 300ish in gear so I thought it might be just me lol. I'm running my electronic shock on max. I don't have an owners manual so I'm not sure where to set anything.
It was suggested to me that I need the 7.1kg big boy spring and a revalve.
Any comments or suggestions would be appreciated.
Thanks

 

[zigoapex1]

Amazing. Are you a career mechanic or something? It's like you're speaking an alien language, lol.

I think this should be stickied...this kind of info is invaluable.

I'm a mechanical engineer and my career is in mechanical design and finite element analysis. I'm a consultant (now) and have done quite a lot of work on things like the Canadarm2 (specifically the SPDM), satellites such as Radarsat, and these days have moved into opto-mechanical design where one of the tasks is to ensure optical elements are positioned to within extreme tolerances over a wide range of temperatures (my most recent thermal compensation system positions a MEMS array of 48 2D mirrors to within "approximately" 0.00003 mm (0.001 thousandths of an inch) while the operating temperature varies anywhere from -5°C to +85°C; the challenge here was the production cost for the system had to be less than $50 and it had to work while experiencing mechanical shock and vibration).

Since my first ride on a 1971 Arctic Cat, over 30 years ago, sledding has always been my passion. Even though I have thoroughly enjoyed building custom vehicles in the past (race cars and off-road trucks, including a 1200hp twin turbo engine and several custom automatic transmissions), I'd prefer to purchase a snowmobile ready to ride (and spend my time sledding, not wrenching). I am very picky and demanding of my snowmobiles though and want to be riding the best performing machine for aggressive trail riding (and this 2007 RTX now hits the mark - after a fair bit of suspension tuning...).

I have to admit I've often thought it would be fun to do some design work on snowmobiles, but have never pursued this line of work.

I bet you had the Master Engineer type III erector set when you were a kid,and put the dam thing together in 15 minutes !
I know your type, My sister works for NASA,and rattles figures off that i
couldn't figure out with a calculator.

 

[MarkAttack]

Yamaha Shock

Shame on Yamaha, they should know more about shocks than other snowmobile manufacturers because of their Motocross Experience.

I have heard that Pioneer does a good re-valve job.

My goal is to purchase a complete Team Fast Platinum Air Suspension for my Yamaha Attak next month.

My stock skid is rather busted up anyway. I am so tired of loosing the hyfax 3 times and taking all of the track clips out. Understand my hyfax was in great shape too because I ride slow in marginal conditions. On an Attak you do have to run the track too tight however to avoid ratcheting, but I will also install external drivers too.

http://www.teamfast.com/products

http://pioneerperformance.net/

 

[Panterawill]

Do the skid pieces have to be put in a jig for gusset welding? I'd like to do the reinforcing myself, if possible, as I've overspent on my budget.

 

[ReX]

Hello Rex,

Would you be willing to share your tweaked valving for the center spring shock? Also is it necessary to replace the center shock spring with a higher rated version? As you posted you re-arched your torsion springs, what method was used? Do you simply bend them with a pipe placed over the long leg of the spring?

I used Carver's valving for the center shock so I can't really share it. As I have suggested to others you could consider using the center shock valve stack from an 07 or newer REV-XP as the valving is similar.

It has been a while but I believe I ended up using the stock spring in the center shock, although I did try to get the heavier spring (I recall it was out of stock for a long time). If you search here I'm sure I posted somewhere which spring I ended up using.

To re-arch them I did just use long pipes and a large vice but I don't want to recommend anyone use this method as it can be dangerous. To make it a bit safer I also put a large, heavy mat on top in case the springs were tempered enough to snap/shatter. They actually were quite easy to re-arch since they seem to be made out of a relatively soft ductile steel. The first time I only raised the ride height a couple of inches and it dropped down quickly again. The second time I went way up (~6-7") and after a few hundred miles they dropped to about 3" higher than stock which was perfect for me (now using the lowest ride height setting). I've put 1000's of miles on them since and they remained at the right height.

A much better option would be to purchase new springs with the right ride height but I spent days looking (in late 2006) and came up with nothing. The "heavy duty" torsion springs that Yamaha sells actually lowered the ride height (I tried 2 sets of them) so unless Yamaha improved them they are of little use (they were stiffer, but configured to lower the ride height).

Also you were going to post pictures of the reinforced front and rear skid arms, do you have any available to post or email me?

Thank you greatly for any assistance. I love the sled except for the ride. I am tired of my ski-doo buddies heckling me.

I always intended to fix up my pivot arms properly and then post pictures of them but unfortunately I've experienced significant health issues. Until this year I haven't really been able to touch my sled (ride or improve) since I started this thread. I never got around to doing the pivot arms right.

My pivot arms were "temporarily" reinforced by a heavy welding shop in order for me to go on a planned tour late in the 07/08 season. The welding is rather "ugly" and reinforcements are excessively heavy (1/4" or 3/8" thick tube sections and plates were used). The guy I normally use for this work was not available at the time (nor were my normal backup welders). I used the pivot arms over a few 1000 miles of aggressive rough riding and they did hold up fine. At the moment I plan to ride as is for this season.

I suppose I could post some pictures of them (if I have some/can find some), but they are not even close to the quality or optimized reinforced design I would normally use/demand.

 

[ReX]

Do the skid pieces have to be put in a jig for gusset welding? I'd like to do the reinforcing myself, if possible, as I've overspent on my budget.

If they aren't broken you can just weld on reinforcements. If broken you need to make sure they are carefully put back together straight and kept in alignment when welded. A jig is a good idea but you still need to make sure you don't build up residual stresses during welding and end up with a distorted arm when taken out of the jig. One method experienced welders sometimes use that also works is to hold them straight, tack weld them together, tweak them (hammer, etc.) perfectly straight and then carefully build up the weld in such a way it doesn't distort the arms.

Personally I usually take my welding jobs to highly experienced welders instead of doing it myself. I have access to a decent TIG welder, but haven't yet spent the time to become good at it.

 

[1litre]

Thanks for the reply Rex. I have since purchased a ZX2 skid and hope to have it installed before the last of the snow disappears in the UP. Revalving did not cure the harsh ride from the stock skid. However I have only bottomed the stock skid only a couple of times.

 

[Jimk]

Rex- I have a 06 Apex GT with a blown rear shock. I am thinking about putting on a Fox Megafloat.
whats our opinion of the Megafloat on an 06?
Do you feel there is a better option?
Jim

 

[MrSled]

Initial post on this thread is now recovered.

 

[Frozenstiff]

Is Rex still around ? I,m in need of some great help with my 07 Yamaha Apex RTX ER.